Apparatus for burning granulated coal



June 30, 1931. w, A N 1,812,080

, APPARATUS FOR BURNING GRANULATED COAL Filed April 1, 1925 3 Sheets-Sheet 1 5 auvewtoz mama June 30, 1931. w; B. CHAPMAN APPARATUS FOR BURNING GRANULATED COAL June 30, 1931. w. B. CHAPMAN APPARATUS FOR BURNING GRANULATED COAL 3 Sheets-Sheet 3 Filed April 1, 1925 awue/nto'c 235 flame 15 erably, such gases are Patented June 30, 1931 WILLIAM B. CHAPMAN, OF JACKSON HEIGHTS, NEW YORK APPARATUS FOR'BUBNING GRANULATED coA Application filed. April 1,

The invention relates to the burning of granular fuel in suspension by means of a combustion chamber having a throat through which a blast of air is projected in an upward direction to float the fuel as it burns in the combustion chamber.

One important object of the invention is to insure that the temperature in such throat will be such during operation as to secure as 1 rapid and complete ignition as possible of the fuel particles. This is accomplished by projecting into said throat an auxiliary current of gases heated sufficiently to maintain ignition temperature in the throat and, prefthemselves combustible and burn in the throat to further assist in igniting the coal. Another object is to prevent the building up upon the walls of ash or unconsumed fuel and to prevent overheating of such walls.

Another object ride for distributing the blast of air from a relatively small nozzle or inlet opening, uniformly throughout a comparatively large combustion chamber.

The invention also aims to provide for the burning of the fuel particles-which are too large to be supported or carried along in the combustion chamber and therefore tend to drop out therefrom without being completely burned. This is done by providing an auxiliary combustion chamber into which such fuel particles may pass and burn and, preferably, the gases and heat developed in such auxiliary combustion chamber pass back into the throat to assist in maintaining ignition temperature therein, as above mentioned.

The invention also includes a boiler construction especially adapted to be used in 0 combination with the features of the invention above referred to and forming a part of the walls of the furnace.

Further objects and advantages of the invention will be in part obvious and in part s )ecifically pointed out in the description of this invention is to pro- 4 liereinaft Serial No. 19,786.

er contained, which taken in connection with the accompanying drawings, discloses one form of apparatus adapted to 0perate in accordance with theinvention; such disclosure, however, is to be considered merely'as illustrative of the principles of the invention. Fig. 1

an apparatus operable in accoidance with the invention.

In the drawingsis a central longitudinal section of Fig. 2'is a horizontal section of such apparatus taken on the line 2-2 of Fig. 1, andlooking in the direction of the arrows.

Fig. 3

Fig. 4 i tached a is a section similar to Fig. 2 but s a detail sectional View showing deform of air blast pipe or nozzle .forming a part of such apparatus.

Fig. 5 is a horizontal section of an apparatus modified in certain respects from the apparatus disclosed in Figs. 1 to 4, said section being taken on lin'e-5-5 of Fig. 6.

Fig. 6

apparatus The invention 18 disclosed in Figs. 1-4 as carried 0 is a central vertical section of the shown in Fig; 5.

ut by an apparatus having a combustionchaniber 1 with a throat 2 at its bottom, such throat being provided in the pres ent instance by a conical base member 4 at the bottom of the combustion chamber. vAn upward blast of air is projected into throat 2 from pipe 6 atsuificient velocity to carry upward the combustion chamber.

usually b which are fed into the In fact the fuel will e fed into the combustion chamber coal particles through pipe 6 along with the primary supply of air. In order perature thereto h to maintain the high ignition temrequired in the region of the throat coarseness of the fuel, I apply eat from an independent source, as

by introducing into such throat a stream of gases heated from an outside source, and these ferably are themselves ofcombusth gases pre ble nature and are caused to burn in the throat. In the present instance fuel is burned within anauxiliary combustion chamber 7 within the brick work walls 5 above described and located directly beneath the throat 2 and the gases developed in this combustion chamber pass upwardly into the throat for the purpose above specified. Preferably only a limited supply of air is suplied to such auxiliary combustion chamber with the result that combustible gases in the nature of producer gas are developed therein.

In the present instance a rotary grate 8 running on an annular shelf 9 supports the fuel in auxiliary combustion chamber 7 such grate being slowly turned in any suitable manner as by means of a pinion l0 engaging an annular gear 11 fixed to the grate. A stationary water-cooled beam 12 is provided slightly above the grate 8 in such manner that as the bed of fuel in chamber 7 turns around the beam 12 agitates and conditions the fuel bed from underneath and continually sweeps out ash from over the grate. As shown the ash travels outwardly along the beam 12 into an opening 13 leading from chamber 7 and drops downwardly through the passageway 14 into a water sealed ash pit 15 from which the ash may be removed as desired.

Air is supplied under pressure to the under side of the grate through a suitable inlet pipe 16, with the result that the combustion chamber 7 operates substantially as a gas producer with its fire bed mechanically agitated and its ash removed by beam 12. The mechanical agitation is advantageous in that it prevents the formation of blow-holes in the fuel bed through which cold air could pass upwardly into throat 2. The gases developed in chamber 7 pass upwardly into the throat 2 where they mix and burn preferably not only with the air and coal supplied through pipe 6, but also with a secondary supply of air which is shown in the present instance as coming in tangentially from pipes 17 into an annular chamber 18' surrounding the conical base member 4 and leading to the throat 2 through a gap 19 at the bottom of member 4 through which the air may pass tangentially into the throat. The secondary air supply thus serves to prevent overheating of the base member 4 and consequent sticking of the fuel thereto, and is itself preheated so as to enter more readily into combustion in the throat. It also assists in maintaining a whirling action of the air and suspended pockets, eddies, stream lines, etc.

This whirling ac-f the combustion chamber by avoiding any tendency toward the formation of dead gas p The path of travel of the hot gases with respect to the surfaces to be heated, is also materially lengthened, affording either-a longer time for heat transfer or a greater velocity of the heating gases, or a combination of these two factors which are advantageous in promoting the efficiency of heat transfer.

Preferably the point of discharge of the primary air blast through pipe 6 into the throat is made adjustable to suit different rates and conditions of operation; in the present instance, a sleeve 20 surrounds the upper end of pipe 6 and may be slid up and down with regard thereto by suitable means such as a lever 21 attached thereto. Preferably a deflector member 22 is mounted on the top of sleeve 20 and provided with fan-like vanes 23 to discharge the coal and air tangentially therefrom and thus. impart a whirl to the coal and air as they enter throat 2 and cause the coal and air to pass spirally upward through combustion chamber 1, which spiral motion will continue as the gases of combustion pass downwardly through the annular chamber 28 hereinafter described. This whirling action will serve to distribute the air and fuel suspended therein more evenly throughout the combustion chamber.

The fuel consumed in chamber 7 may be supplied partly or wholly from an outside source, if desired, but I prefer to make use of this auxiliary combustion chamber to complete the combustion of fuel particles which are projected into the combustion chamber 1 but agglomerate therein, or are so heavy that they drop out of the chamber without being consumed. As shown, any large particles may drop directly through the throat 2 on to the bed of fuel supported by grate 8 and thus the apparatus will operate efliciently without necessitating the expense of pulverizing the fuel employed to the customary exceedingly fine and uniform state of division. Uusually it will be possible to regulate the rate of combustion and ash removal in chamher 7, to enable the entire supply of fuel thereto to be obtained from fuel particles which drop as aforesaid. Adjustment of the height of sleeve 20 will also serve to regulate the proportion of fuel going into the auxiliary chamber 7, since changing the height changes the velocity near the walls of the throat.

In the apparatus disclosed, the combustion chamber 1 is enclosed within an annular set of boiler tubes 24 connected to an annular header 25 at their bottoms and bent at their tops to converge into a header or drum 26 which is located above the combustion chamber. The tubes 24: will be all accessible for cleaning purposes through a manhole 26 in ber 1 are formed by refractory blocks 27 and 27a loosely assembled into spaced columns fitting in between the inner set of annular being vertically slidable with regard to each ering chamber.

openings 38 are provided in ings 38, producing a more even other may be readily demounted for replacements, repairs, etc. Preferably suitable baffle members 30 are provided in chamber 28 past which the gases flow downwardly to an annular gathering chamber 31 which surrounds the auxiliary combustion chamber 7. Suitable devices are provided to balance the draft throughout different portions of said gathering chamber, such as dampers 32,00- operating with ports 33, leading to the gath- By proper adjustment of the dampers 32 the flow of the gases of combustion in different zones'in the annular set of tubes may be equalized. The exhaust gases finally pass out through a fine 34 (Fig. 2 Access may be had to the chamber underneath the grate 8 through a manhole 35 and to the gathering chamber 31'through a man hole 36 (Fig. 2). The door-opening 13 provides access to the auxiliary chamber 7 and the sleeve 20 may be dropped far enough to enable the deflector member 22 to be reached through the doorway.

In the operation of the apparatus above described, the greatest velocity of the gases will be in the region of throat 2 and the gases will gradually rise in combustion chamber 1 as the finely divided coal carriedalong wlth the rising gaseous column, will be burned The gases travel downwardly as they give up their heat to the boiler tubes and aredistributed near the bottom of the apparatus, to which point only the gases which have given up the greatest proportion of their heat Wlll fall.

In Figs. 5 and 6 I have disclosed a type of furnace generally similar to the one abovedescribed but differing therefrom in that the fuel and primary air are fed in through an annular water-cooled member 37 which is located at the base of the combustion chamber 1, at throat 2. A plurality of tangential member 37 through which openings air and fuel are supplied through pipes 39 leading from a. main feed pipe 40 which surrounds the furnace. As shown the member 37 and the several i pipes 39 are water cooled by means of jackets 41 which surround the respective pipes and lead to member 37".

The member 37 thus serves to impart a whirl to the air and fuel fed in through opendiffusion of the draft and fuel throughout chambci 1. The upper draft through throat 2 from auxiliary chamber 7 serves to cause the air and fuel to pass upwardly and preferably the pipes 39 are somewhat upwardly inclined as shown in Fig. 6 in order to assist further in projecting the primary air and fuel up into the combustion chamber. In other respects the embodiment of .the invention shownin Figs. 5 and 6 operates as previously set forth in connection with Figs. 1 to 4.

The invention as above described provides for the burning both of very fine fuel particles and larger fuel particles, thus making it possible to employ coal which has been merely crushed or granulated without the necessity of going to the expense of obtaining an exceedingly fine and uniform degree of pul- I verization. Reference in the claims to finely divided fuel accordingly should be construed as including both uniform and nonuniform sizes of fuel.

4 WVhile the invention has been disclosed as carried out by the above described'apparatus, it' should be understood that many changes may be made therein without departing from its principles as defined in the following claims:

I claim:

1. In combination an annular upstanding set of boiler tubes enclosing a combustion chamber, means for projecting a blast of air upwardly into said combustion chamber to suspend fuel therein, an auxiliary combustion'chamber located beneath said first mentioned chamber, means for conducting the gases of combustion downwardly past said tubes from said first mentioned combustion chamber, and a gathering chamber for the Zpent gases surrounding said auxiliary chamstantially longitudinally along one or more sides of said combustion chamber, headers for said tubes located respectively adjacent the top and bottom of said combustion chamber, means for setting up within said cham- 2. In combination an annular upstanding ber a current of air and suspended granulat- 1 ed fuel which whirls centrifugally out to- Ward said tubes While passing longitudinally through said combustion chamber, and an auxiliary combustion chamber located beneath said first mentioned combustion cham- 5 ber adapted to consume fuel dropping out of the above mentioned current.

In testimony that I claim the foregoing, I have hereunto set my hand this 10th day of March, 1925.

WILLIAM B. CHAPMAN. 

